If the perennial classic Are You There God? It's Me, Margaret had one overriding message, it's that getting your first period is an OMG Big Deal. But beyond the fictionalized account of a 12-year-old freaking out about bulky feminine products, it turns out that there's one aspect to the story that wasn't covered: Margaret may have gotten an advantage over her older peers who were still waiting their turn.

Getting your period on the early side of the teen years could have a beneficial effect on fertility later on, but it may set you up for some female trouble, too, according to Judith Marcin, M.D., a Healthline.com medical reviewer and family medicine physician in Chicago.

Before we jump in, a quick primer:

"Early menarche" is defined as starting menstruation at or before the age of 12, which happens to about 10 percent of girls. Late menarche is after the age of 14, and Marin notes that if someone still hasn't gotten that first visit from Aunt Flo by 16, she should get a medical work up to determine why the delay might be occurring.

If you're a Margaret after all, what can you expect? A mixed bag, it turns out:

1. Early bloomers may be fertile sooner, and not just because they got their periods first.

Just because your period begins, it doesn't mean you're suddenly completely fertile, Marcin says, because not all cycles produce eggs during those first years—and that's especially true for those experiencing early menarche. At the beginning, only about half of cycles will be ovulatory and then they begin increasing each year.

So, that means early bloomers can expect to have full-on fertility (if all else is going well) in their late teens. But with later menarche, it can take longer to get up to speed—often, it can be eight to 12 years before all cycles are ovulatory, according to Marcin. Someone who gets her first period at age 16, then, could have to wait until her late 20s before every cycle pops out eggs, even though her first period came only four years after her early-period friends.

2. And they are likely to be fertile for longer overall.

"In general, women with early menarche will have more years of fertility because they'll have more cycles of ovulation compared to later onset menarche, assuming that menopause is on schedule," Marcin says. She adds that the start of menopause, which is typically between 48 and 52, doesn't change based on whether you got your first period earlier or later.

3. Good news: Your bones are probably stronger.

For the early-onset types, more exposure to estrogen over a lifetime has another added benefit, Marcin notes: lower risk of osteoporosis.

Literally meaning "porous bone," this condition causes weakened bones that can lead to fractures and general bone loss. Researchers have noted that there's a direct relationship between the lack of estrogen after menopause and the development of osteoporosis.

That's why those with early menopause—before age 45—often have big-time problems with bone density, because once that estrogen starts dropping, so does bone mass.

If you're petite and have a family history of osteoporosis, then welcome to your position behind the 8-ball of bone loss. But there are therapies that are used to help, like hormone replacement and supplementing with calcium and vitamin D.

4. Bummer news: Risk of breast cancer is higher, thanks to all those years of estrogen.

Now for the downside to all that juicy estrogen. "There's more risk of breast cancer for those who have earlier menarche due to longer lifetime exposure to estrogen," says Marcin. So, your bones are great, but your boobs need to be checked.

About two out of three breast cancers are hormone receptor-positive, which means that malignant cells attach to estrogen. When that happens, high estrogen levels help the cancer cells grow and spread.

That's why late menopause is also a risk—the longer that estrogen courses through your system, the more you need to stay on top of the breast checks.

There's nothing you can do to change up your menstruation start date—and let's face it, if you had a time machine, would you really choose your first period as the thing to fix?—but you may want to talk to your doc about how that longer exposure to estrogen could affect you. We think that's what Margaret would do.